Synoptic mosaic panels which are found in power stations, for example, are formed of a series of horizontal and vertical supports to which are mounted control instruments, such as switches, the surface of indicating instruments, such as pilot lamps as well as tiles, the surface of which is either blank or displays indicia representing circuitry or other useful information to the operator. In some panels, certain tiles have a transparent surface portion allowing light to be in order to transmitted from a light source mounted to the panel supports to draw the operator's attention.